U.S. patent application number 12/572819 was filed with the patent office on 2010-05-20 for cleaning apparatus and printing apparatus.
This patent application is currently assigned to Seiko Epson Corporation. Invention is credited to Kenichi MURAHASHI.
Application Number | 20100123753 12/572819 |
Document ID | / |
Family ID | 42171683 |
Filed Date | 2010-05-20 |
United States Patent
Application |
20100123753 |
Kind Code |
A1 |
MURAHASHI; Kenichi |
May 20, 2010 |
CLEANING APPARATUS AND PRINTING APPARATUS
Abstract
A cleaning apparatus, which cleans a print head of a printing
apparatus in response to a start trigger for regular cleaning,
includes a sound sensor that detects a sound of the operational
environment of the printing apparatus, a determination unit that
determines whether the operational environment is quiet or not
based on a comparison result between detected sound of the sound
sensor and a threshold value, and a controller that delays the
start of the regular cleaning by holding the start trigger until
the operational environment becomes quiet based on a determination
result of the determination unit when the start trigger for the
regular cleaning has occurred.
Inventors: |
MURAHASHI; Kenichi;
(Kitakyushu, JP) |
Correspondence
Address: |
GLOBAL IP COUNSELORS, LLP
1233 20TH STREET, NW, SUITE 700
WASHINGTON
DC
20036-2680
US
|
Assignee: |
Seiko Epson Corporation
Tokyo
JP
|
Family ID: |
42171683 |
Appl. No.: |
12/572819 |
Filed: |
October 2, 2009 |
Current U.S.
Class: |
347/19 ;
347/22 |
Current CPC
Class: |
B41J 2/17509 20130101;
B41J 29/38 20130101; B41J 2/165 20130101 |
Class at
Publication: |
347/19 ;
347/22 |
International
Class: |
B41J 29/393 20060101
B41J029/393; B41J 2/165 20060101 B41J002/165 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2008 |
JP |
2008-295681 |
Claims
1. A cleaning apparatus that cleans a print head of a printing
apparatus, which performs printing by ejecting ink, in response to
a start trigger for regular cleaning, the cleaning apparatus
comprising: a sound sensor that detects a sound of operational
environment of the printing apparatus; a determination unit that
determines whether the operational environment is quiet or not
based on a comparison result between detected sound of the sound
sensor and a threshold value; and a controller that delays start of
the regular cleaning by holding the start trigger until the
operational environment becomes quiet based on a determination
result of the determination unit when the start trigger for the
regular cleaning has occurred.
2. The cleaning apparatus according to claim 1, wherein the
determination unit stores the threshold value, which is set between
a minimum value of the sound of the operational environment up to
just before printing until a printing mechanism operates to perform
the printing after a print job occurs in the printing apparatus,
and a minimum value of the sound of the operational environment
through the day, and determines whether the operational environment
is quiet or not by comparing the detected sound of the sound sensor
with the threshold value in response to the start trigger.
3. The cleaning apparatus according to claim 2, wherein the
threshold value is updated through a learning process based on
repeated determination of the minimum value of the sound of the
operational environment during a period up to just before the
printing, and the minimum value of the sound of the operational
environment through the day.
4. The cleaning apparatus according to claim 1, wherein the
printing apparatus includes a receipt printer which is connected to
a host computer of a POS system.
5. A printing apparatus comprising the cleaning apparatus according
to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Japanese Application No.
2008-295681 filed on Nov. 19, 2008. The entire disclosure of
Japanese Application No. 2008-295681 is incorporated herein by
reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a cleaning apparatus that
cleans a print head of a printing apparatus, which performs
printing by ejecting ink, and the printing apparatus, and more
particularly, relates to control of a start timing of regular
cleaning which is carried out automatically in the printing
apparatus.
[0004] 2. Related Art
[0005] According to the related art, ink jet printers have been
used as receipt printers of a POS system for convenience stores or
the like.
[0006] The ink jet printer performs predetermined printing by
ejecting ink of an ink cartridge from a print head to receipt paper
or the like. According to such an ink jet printer, in order to
prevent the viscosity of ink remaining in nozzles of the print head
from being increased and to prevent bubbles from penetrating into
the inside of the print head from the nozzles, regular cleaning is
automatically performed to clean the print head by absorbing the
ink from the nozzles of the print head, so that printing is always
performed in a proper state.
[0007] Further, since a nozzle formation surface of the print head
faces the paper while being spaced apart from the paper at a
predetermined interval, paper dust, ink or the like may be easily
attached to the nozzle formation surface. If the paper dust, ink or
the like are attached to the nozzle formation surface, holes of the
nozzles may be clogged or the paper may be contaminated due to the
ink attached thereto. In order to solve these problems, the regular
cleaning is performed to wipe impurities attached to the nozzle
formation surface by using an elastic absorption plate, so that a
printing operation can be always performed in a proper state.
[0008] In general, the regular cleaning is automatically performed
after a predetermined time lapses from the previous cleaning. Thus,
in a receipt printer employing the ink jet printer, a start timing
of the regular cleaning may be reached while a receipt to be
provided to a product purchaser is being printed. In such a case,
cleaning must be performed after the printing process is primarily
performed, or the printing process must be temporarily stopped so
that the cleaning can be primarily performed. However, if the
cleaning is primarily performed and thus the purchaser has to wait
for a predetermined time until the cleaning is completed, the
reputation of the convenience store may be adversely affected in
terms of service quality. In contrast, if the printing process is
primarily performed so that the regular cleaning is delayed, since
cleaning is not performed for a long time, the print quality of the
receipt or the like may be degraded.
[0009] Further, the start timing of the regular cleaning may be
reached during the printing process in an ink jet printer serving
as an image recording apparatus in which continuous printing is
performed, as well as an ink jet printer used in an office and a
household (see paragraphs 0002 to 0014 and 0033 to 0072, and FIGS.
4A to 7 of JP-A-2008-68438).
[0010] According to patent document 1, in the ink jet printer
serving as the image recording apparatus, if the start timing of
the regular cleaning for the print head is reached during the
printing process, the printing process is temporarily stopped at a
proper timing in consideration of the remaining number of papers to
be printed and then the cleaning is performed, so that the
workability is improved and the print quality is prevented from
being degraded. However, in such a case, the printing process is
essentially stopped.
[0011] In this regard, there has been proposed a scheme for
calculating a low print time zone, in which the printing quantity
is equal to or less than a predetermined value, from the previous
history of a printing operation in such a printing apparatus which
uses the ink jet printer such as the receipt printer, and regular
cleaning is performed in the low print time zone, so that the
regular cleaning is performed at a proper timing corresponding to
the operational environment of the printing apparatus while
preventing the printing process from overlapping the regular
cleaning (see paragraphs 0013 to 0015 and 0042 to 0064, and FIGS. 4
to 10 of JP-A-2007-98706).
[0012] However, although the regular cleaning is performed in the
low print time zone calculated based on the previous history as
disclosed in JP-A-2007-98706, a printing process for printing a
receipt or the like may be necessarily performed in the low print
time zone under an operational environment in which the printing
process for printing the receipt or the like happens irregularly in
a convenience store or the like. At this time, if the regular
cleaning is performed, the purchaser or the like must wait until
the cleaning is completed. Further, in the printing apparatus of a
convenience store open 24 hours a day under the operational
environment in which the printing process for printing the receipt
or the like happens irregularly through the day, the above problem
must be solved.
SUMMARY
[0013] An advantage of some aspects of the invention is that it
starts regular cleaning at an optimal timing, at which no wait time
of a printing process occurs, under the operational environment as
described above.
[0014] According to an aspect of the invention, there is provided a
cleaning apparatus that cleans a print head of a printing
apparatus, which performs printing by ejecting ink, in response to
a start trigger for regular cleaning, the cleaning apparatus
including a sound sensor that detects a sound of the operational
environment of the printing apparatus, a determination unit that
determines whether the operational environment is quiet or not
based on a comparison result between detected sound of the sound
sensor and a threshold value, and a controller that delays the
start of the regular cleaning by holding the start trigger until
the operational environment becomes quiet based on a determination
result of the determination unit when the start trigger for the
regular cleaning has occurred.
[0015] In such a case, while the printing apparatus is printing a
receipt or the like, the level of the sound (noise) of the
operational environment of the printing apparatus is increased due
to the printing sound of the printing apparatus or the sound of the
motion or voice of a purchaser waiting to pay the purchase price.
When the start trigger for the regular cleaning has occurred, the
level of the sound of the operational environment of the printing
apparatus, which is detected by the sound sensor, is increased due
to the printing sound of the receipt or the like or sound generated
from the purchaser waiting to pay the purchase price. If the
operational environment of the printing apparatus is not quiet, the
controller can delay the start of the regular cleaning by holding
the start trigger until the operational environment becomes quiet
based on the determination result of the determination unit on the
basis of a result obtained by comparing the detected sound of the
sound sensor with the threshold value. Thus, the regular cleaning
can be performed when no printing of the receipt or the like is
actually performed and no purchaser waiting to pay the purchase
price is present, regardless of time zone or the like. Under
various operational environments, the regular cleaning can be
performed at an optimal timing at which no wait time of a printing
process occurs.
[0016] Further, the determination unit of the cleaning apparatus of
the invention stores the threshold value, which is set between a
minimum value of the sound of the operational environment up to
just before printing until a printing mechanism operates to perform
the printing after a print job is started in the printing
apparatus, and a minimum value of the sound of the operational
environment through the day, and determines whether the operational
environment is quiet or not by comparing the detected sound of the
sound sensor with the threshold value in response to the start
trigger.
[0017] In such a case, if the threshold value is larger than the
minimum value of the sound of the motion or voice of a purchaser
waiting to pay the purchase price except for the sound (i.e.,
printing sound) of the operational environment up to just before
printing until the printing mechanism operates after the print job
is started, the regular cleaning may overlap the printing process
of the receipt or the like, which is provided to a customer waiting
to pay the purchase price. Further, if the threshold value is set
to be equal to or less than the minimum value of the sound of the
operational environment through the day, although the operational
environment becomes quiet, the regular cleaning may not be
performed. However, the threshold value is set between the levels
of such sounds and the detected sound of the sound sensor is
compared with the threshold value, so that the above problems can
be prevented from occurring and it is possible to exactly determine
whether the operational environment is quiet. Further, it is
possible to provide a detailed configuration in which the optimal
timing at which no wait time of the printing process occurs can be
estimated and then the regular cleaning can be performed.
[0018] Further, the threshold value is preferably updated through a
learning process based on repeated determination for the minimum
value of the sound of the operational environment during a period
up to just before the printing, and the minimum value of the sound
of the operational environment through the day.
[0019] In such a case, the threshold value is updated to the
optimal value through the learning process based on the change in
the sound of the operational environment, and the regular cleaning
can be performed at the optimal timing at which no wait time of the
printing process occurs.
[0020] Further, the printing apparatus includes a receipt printer
which is connected to a host computer of a POS system.
[0021] The printing apparatus of the invention is provided with the
cleaning apparatus having the configuration as described above can
estimate the optimal timing at which no wait time of the printing
process occurs and then can perform the regular cleaning under
various operational environments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0023] FIG. 1 is a view showing a POS system according to one
embodiment of the invention.
[0024] FIG. 2 is a perspective view showing an ink jet printer
shown in FIG. 1.
[0025] FIG. 3 is a perspective view showing the main elements of an
ink jet printer shown in FIG. 1.
[0026] FIG. 4 is a block diagram showing functions of an ink jet
printer shown in FIG. 1.
[0027] FIG. 5 is a graph showing an example of the change in the
level of detected sound of a sound sensor through the day in FIG.
1.
[0028] FIG. 6 is a graph showing the change in the level of
detected sound of a sound sensor during printing in FIG. 1.
[0029] FIG. 7 is a flow chart showing an operation of a cleaning
controller shown in FIG. 4.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0030] Hereinafter, one embodiment of the invention will be
described with reference to FIGS. 1 to 7.
Entire Configuration
[0031] FIG. 1 is a view schematically showing the configuration of
a POS system according to the embodiment of the invention. For
example, the POS system includes a host computer 300, which is
installed in the inside of a convenience store open 24 hours a day
or an office out of the convenience store, and an ink jet printer 1
which is installed at a counter in the convenience store while
being connected to the convenience store in a wired or wireless
manner and which serves as a receipt printer. The ink jet printer 1
is always in a state capable of printing except for an exceptional
period such as regular cleaning to be described later. If print
data based on reading of barcodes of products is received from the
host computer 300, the ink jet printer 1 prints receipts or coupons
on an irregular basis. Then, the printed receipts or coupons are
given to a purchaser, who has paid the purchase price, through a
clerk or a worker.
[0032] The ink jet printer 1 serving as the printing apparatus of
the invention is provided with the cleaning apparatus of the
invention, which will be described later. FIG. 2 is a front
perspective view showing the ink jet printer 1. FIG. 3 is a rear
perspective view showing the main parts in a body 14 of the ink jet
printer 1.
[0033] As shown in FIGS. 2 and 3, the ink jet printer 1 includes a
print head 2 for ejecting ink, a carriage 3 provided with the print
head 2, a transfer mechanism 4 for transferring the carriage 3 in
the scanning direction indicated by an arrow A of FIG. 2, and an
ink supply mechanism 5 for supplying ink to the print head 2.
Further, the body 14 of the ink jet printer 1 is provided at a
proper position of the rear surface (see FIG. 1) or the side
surface thereof with a container 14a of a sound sensor 24 that
detects sound of the operational environment in the convenience
store. The sound sensor 24 detects sound (noise) in the convenience
store, and may include a small-sized microphone having a simple
configuration. However, the sound sensor 24 may have various
configurations.
[0034] As shown in FIGS. 2 and 3, the print head 2 includes a
nozzle formation surface 7 having a rectangular shape, which is
provided with a plurality of nozzles 6 that eject ink. The nozzle
formation surface 7 is exposed through a rectangular opening 8
which is formed in the carriage 3. The transfer mechanism 4
transferring the carriage 3 from side to side includes a guide
shaft 9, a timing belt 12 installed between a driving pulley 10 and
a driven pulley 11, and a carriage motor 13 that rotates the
driving pulley 10. The lower surface of the carriage 3 is supported
by the guide shaft 9 to slidably move along the guide shaft 9, and
is connected to the timing belt 12. Thus, if the timing belt 12 is
rotated by the carriage motor 13, the carriage 3 moves along the
guide shaft 9 in the scanning direction A shown in FIG. 2.
[0035] While the carriage 3 is moving in the scanning direction A
as described above and a paper P wound in a roll form is being
transported, the ink supplied from the ink supply mechanism 5 is
ejected toward the paper P from the nozzles 6 of the print head 2,
so that printing is performed. That is, the paper P is transported
at the position facing the nozzle formation surface 7 and an amount
of money or the like is printed on the surface of the paper P by
the ejected ink droplets. The ink supply mechanism 5 includes an
ink cartridge 16, which is detachably installed at an ink cartridge
installation unit 15 provided in the body 14 of the ink jet printer
1, a pressure attenuator 17 installed in the carriage 3, and an ink
supply pipe 18 that connects the ink cartridge 16 to the pressure
attenuator 17.
[0036] The ink cartridge 16 includes a hard case 19 and a flexible
ink receiving section 20 received in the hard case 19. An ink
supply injector 22 installed at one end of the ink supply pipe 18
is connected to an ink discharge port 21 formed in the ink
receiving section 20. The pressure attenuator 17 is connected to
the other end 23 of the ink supply pipe 18. Thus, ink stored in the
ink receiving section 20 of the ink cartridge 16 is supplied to the
pressure attenuator 17 through the ink supply pipe 18, and is then
supplied to the print head 2. Consequently, the ink supplied to the
print head 2 is ejected from the nozzles 6.
[0037] A cleaning unit 100 (a mechanism unit of the cleaning
apparatus of the invention) is installed at the position facing a
home position of the carriage 3, which is indicated by an arrow C
of FIG. 3. The cleaning unit 100 is prepared in the form of an ink
recovery mechanism for cleaning the print head 2 and includes a
head wiping mechanism 101 and an ink absorbing mechanism 104.
Ink Absorbing Mechanism
[0038] The ink absorbing mechanism 104 includes a cap 105 that
covers the nozzle formation surface 7 of the print head 2 when the
print head 2 has moved to the home position C. The cap 105 is
withdrawn to a side of a unit case 106 while the carriage 3 is
passing through a recording area B. Then, if the carriage 3 moves
into the home position C, the cap 105 protrudes forward from the
unit case 106 to cover the nozzle formation surface 7 of the print
head 2.
[0039] Inner pressure of the cap 105 is reduced by a pump 108 which
is driven by a motor 107 installed in the unit case 106. Thus, the
pump 108 is driven in a state in which the cap 105 covers the
nozzle formation surface 7, so that an ink absorbing process
(cleaning) can be performed to absorb the ink from the nozzles 6
and discharge the ink. As a result of the ink absorbing process,
bubbles in the print head 2 or ink having high viscosity can be
removed, so that the ink in the print head 2 can be returned to a
proper state.
Head Wiping Mechanism
[0040] As shown in FIG. 2, the head wiping mechanism 101 includes
an elastically transformable blade 102 and a blade support member
103 that supports the blade 102. The blade support member 103 be
moved by the motor 107, which is installed in the unit case 106,
through a transfer mechanism (not shown) such as a gear train,
which is installed in the unit case 106. Further, the blade support
member 103 is withdrawn in the unit case 106 and protrudes from the
unit case 106. If the blade 102 protrudes from the unit case 106, a
front end of the blade 102 makes contact with the nozzle formation
surface 7 to wipe ink or paper dust attached to the nozzle
formation surface 7 when the carriage 3 has moved into the home
position C from the print area B.
Driving Control System
[0041] The print operation of the print head 2, the operation of a
transport mechanism (not shown) of the paper P, and the operation
of the ink absorbing mechanism 104 and the head wiping mechanism
101 or the like in the ink jet printer 1 are controlled by a
driving control apparatus 200 which forms a circuit unit of the
cleaning apparatus of the invention and includes a microcomputer as
a main element.
[0042] That is, the driving control apparatus 200 controls the
driving of each element of the ink jet printer 1 by using working
areas of a RAM (not shown) based on control program stored in
advance in a ROM (not shown).
[0043] FIG. 4 is a block diagram showing the function of the
driving control system. The driving control system has a print
control function, a transport control function, and start and
driving control functions of the cleaning unit 100 that cleans the
print head 2. Unless otherwise noted, the cleaning of the print
head 2 in the embodiment includes one of the ink absorbing
operation, which is performed by the ink absorbing mechanism 104
with respect to the nozzles 6, and the wiping operation of wiping
ink or paper dust attached to the nozzle formation surface 7, which
is performed by the head wiping mechanism 101, or includes a
process obtained by combining the ink absorbing operation with the
wiping operation. The regular cleaning is automatically performed
based on a start trigger for cleaning, which is generated every
predetermined period.
[0044] A print driving controller 201 shown in FIG. 4 controls the
driving of the carriage motor 13 and the print head 2 through
drivers 202 to perform the desired printing on the paper P. A
transport controller 203 controls the driving of a paper transport
mechanism 205 such as a transport motor through a driver 204 in
cooperation with the printing operation.
[0045] A cleaning unit controller 206 shown in FIG. 4 starts an
operation in response to a cleaning start trigger (start signal)
such as regular cleaning from a cleaning controller 208, thereby
controlling the cleaning of the print head 2 through the ink
absorbing mechanism 104, which includes an absorbing motor 107 or
the like, via a driver 207. When cleaning the print head 2, the
cleaning unit controller 206 drives the carriage 3 or the like to
move the print head 2 to a predetermined position, and controls
driving of the cleansing unit 100 to perform a predetermined ink
absorbing operation and head wiping operation.
[0046] After a cleaning controller 208 serving as a control device
of the invention receives a time signal of a clock unit 209, the
start trigger for the regular cleaning of a maintenance timer 211,
and a determination result of an operational environment sound
determining unit 210, the cleaning controller 208 holds the start
trigger for the regular cleaning until the operational environment
becomes quiet based on determination information from the
operational environment sound determining unit 210 that receives
detected sound from the sound sensor 24, and delays output of the
start trigger for the regular cleaning to the cleaning unit
controller 206 until the operational environment becomes quiet.
Detected sound of Sound Sensor 24
[0047] The sound sensor 24 operates while the ink jet printer 1 is
turned on, and normally detects the sound of the operational
environment of the ink jet printer 1 through the day (for 24
hours), that is, sound in the convenience store. The detected sound
includes the printing sound (mechanical operation sound) of the ink
jet printer 1, sound generated from a clerk or a purchaser or the
like. However, the detected sound mainly includes the sound of a
clerk and a purchaser talking, except for the printing sound, up to
just before the ink jet printer 1 does not perform printing. In
general, with the increase in the number of purchasers who wait to
pay the purchase price, the level of the detected sound is
increased. Meanwhile, at midnight and early in the morning when no
purchaser is present and no printing is performed by the ink jet
printer 1, the detected sound is at a minimum level.
[0048] Further, for example, the sound detected by the sound sensor
24 through the day changes as shown in FIG. 5. As it can be seen
from FIG. 5, if a purchaser enters the convenience store and the
printing sound or talk sound is generated at midnight and early in
the morning, the level of the detected sound is increased. In
addition, the printing sound of the ink jet printer 1 includes
operation sound (mechanical sound) of the printing mechanism when
the ink jet printer 1 actually performs printing in response to a
print job generated after the ink jet printer 1 receives print data
from the host computer 300.
Processing of Operational Environment Sound Determining Unit 210
Setting of Threshold Value
[0049] Further, since the level of the detected sound of the sound
sensor 24 is increased due to the printing sound of the ink jet
printer 1 and the sound of the motion or voice of a purchaser
waiting to pay the purchase price, the operational environment
sound determining unit 210 determines whether the operational
environment is quiet or not by comparing the detected sound of the
sound sensor 24 with a threshold value (decibel value) of a
suitable size, so that the start of the regular cleaning is held
based on the comparison result regardless of time zone or the like
when the operational environment is not quiet due to printing by
the ink jet printer 1 or the purchaser waiting to pay the purchase
price. Thus, the ink jet printer 1 completes the printing, so that
no purchaser has to wait for completion of the printing. In
addition, the start of the regular cleaning can be delayed until
the operational environment becomes quiet.
[0050] The threshold value, which serves as a reference (i.e., a
determination reference for quietness of the operational
environment) used to determine whether to hold the start of the
regular cleaning, can be set by collecting sound of the operational
environment of the ink jet printer 1 through the day. However, at
that time, if the threshold value is set to be equal to or less
than minimum detected sound a during a day as shown in FIG. 5, when
detected sound larger than the minimum detected sound .alpha. is
obtained, the regular cleaning is not performed. As a result, the
regular cleaning may not be completely performed.
[0051] Meanwhile, the presence or absence of a purchaser waiting to
pay the purchase price can be determined from a result obtained by
determining whether the level of ambient environment sound, except
for the printing sound of the ink jet printer 1, is increased due
to the sound of the motion or voice of a purchaser waiting to pay
the purchase price. Further, since detected sound up to just before
a print job is started in the ink jet printer 1 so that printing is
performed and thus the printing mechanism operates becomes the
latest detected sound such as the sound of the motion or voice of
the purchaser waiting to pay the purchase price, the threshold
value may be set to be equal to or larger than a minimum value
.beta. of detected sound during a day as shown in FIG. 5 up to just
before the print job is started in the ink jet printer 1 so that
the printing is performed and thus the printing mechanism operates.
However, in such a case, when the level of environmental noise is
reduced due to unknown factors and thus the level of the printing
sound detected from the ink jet printer 1 is reduced, the regular
cleaning may be performed while the printing is being performed.
For example, if a range around 12 o'clock on a time axis shown in
FIG. 5 is extended, FIG. 6 is obtained.
[0052] In this regard, after the operational environment sound
determining unit 210 serving as a determination device of the
invention together with a non-volatile memory 212 writes sampling
data of small time intervals, which is obtained from detected sound
of the sound sensor 24 through the day, in the non-volatile memory
212 together with information such as the print execution time of
the ink jet printer 1 such that the sampling data and the
information are collected, the operational environment sound
determining unit 210 detects the minimum value .alpha. of all the
detected sounds at a corresponding date as the lowest limit value
and the minimum value .beta. up to just before printing at the
corresponding date as the upper limit value at a predetermined time
with reference to the collection result of the previous time (e.g.,
the other day) through the day, and, for example, calculates a
threshold value R of a suitable size between the lowest limit value
(minimum value .alpha.) and the upper limit value (minimum value
.beta.) from a weighted average operation
(A.times..alpha.+B.times..beta.)/2. The operational environment
sound determining unit 210 then stores the threshold value R in the
non-volatile memory 212, such as an EEPROM or a flash memory which
permits rewriting, in order to set the suitable threshold value R
as a determination reference used when it is determined whether an
operational environment is quiet. In this way, the regular cleaning
is performed as necessary and can be performed without overlapping
a printing process. Further, in the average operation formula, A
and B denote weighted coefficients.
[0053] The threshold value R may be initially set one time.
However, in order to improve reliability or the like, it is
preferred to regularly update the threshold value R every day or
every month or similar. Further, through the updating, the
threshold value R may be completely replaced with the latest
threshold value calculated this time. For example, it is preferred
to update the threshold value through a learning process in
consideration of the previous threshold value R from an operation
(C.times.current R+D.times.latest R)/2 based on the current
threshold value R in the non-volatile memory 212 and the latest
threshold value R calculated this time. Further, it is preferred to
update the threshold value R at a predetermined time at midnight or
early in the morning for which the number of purchasers is small.
In the above operation formula, C and D denote weighted
coefficients.
Determination Process
[0054] On the basis of the threshold value R set as described
above, if the start trigger for the regular cleaning is received
from the maintenance timer 211, the operational environment sound
determining unit 210 repeatedly compares the latest detected sound
of the sound sensor 24 with the threshold value R stored in the
non-volatile memory 212 until the determination result is changed
to a holding-release level to be described later. Then, if the
latest detected sound of the sound sensor 24 has a value lower than
the threshold value R, the operational environment sound
determining unit 210 outputs the determination result, which
represents that a hold-maintenance level is changed to the
hold-release level, to the cleaning controller 208.
Process of Cleaning Controller 208
[0055] Hereinafter, a process by which the cleaning controller 208
controls the regular cleaning will be described with reference to a
flow chart shown in FIG. 7.
[0056] If the start trigger for the regular cleaning is received
from the maintenance timer 211, the cleaning controller 208 stores
the trigger in a register or the like to hold the output thereof
(Steps S1 and S2 shown in FIG. 7). Then, the cleaning controller
208 waits until the operational environment of the ink jet printer
1 becomes quiet based on the determination result of the
operational environment sound determining unit 210, which
represents that the hold-maintenance level is changed to the
hold-release level (Steps S2 and S3 shown in FIG. 7). When the
level of the detected sound of the sound sensor 24 is increased
because the ink jet printer 1 prints a receipt or the like or a
purchaser waiting to pay the purchase price is present, the
cleaning controller 208 does not start the regular cleaning.
[0057] Then, if the operational environment of the ink jet printer
1 becomes quiet, or no purchaser waiting to pay the purchase price
is present after printing of the ink jet printer 1 is completed,
the determination result of the operational environment sound
determining unit 210 represents that the hold-maintenance level is
changed to the hold-release level, so that the holding of the start
trigger for the regular cleaning is released and the start trigger
is output to the cleaning unit controller 206 so that the cleaning
unit controller 206 is driven (Steps S3 and S4 shown in FIG.
7).
Process of Cleaning Unit Controller 206
[0058] The cleaning unit controller 206 driven in response to the
start trigger for the regular cleaning controls driving of the
cleaning unit 100 through the driver 207 as described above to
perform the predetermined ink absorbing operation and head wiping
operation with respect to the print head 2, so that the regular
cleaning is performed with respect to the print head 2.
[0059] Further, the sound sensor 24, the cleaning unit 100, the
cleaning unit controller 206, the driver 207, the cleaning
controller 208, the clock unit 209, the operational environment
sound determining unit 210, the maintenance timer 211 and the
non-volatile memory 212 constitute the cleaning apparatus of the
print head 2.
[0060] According to the embodiment, when the start trigger for the
regular cleaning has occurred, if the operational environment (the
inside of the convenience store) of the ink jet printer 1 is not
quiet because the level of the detected sound of the sound sensor
24 is increased due to the printing sound of a receipt or the sound
of the motion or voice of a purchaser waiting to pay the purchase
price, the cleaning controller 208 holds the start trigger until
the operational environment of the ink jet printer 1 becomes quiet,
so that the start of the regular cleaning can be delayed. Thus, the
regular cleaning can be performed by exactly estimating an optimal
timing, at which no printing of a receipt or the like is actually
performed and no purchaser waiting to pay the purchase price is
present, regardless of time zone or the like. In particular, in a
convenience store open 24 hours a day, the service quality can be
prevented from being degraded due to the regular cleaning.
Consequently, it is possible to provide a receipt printer serving
as an ink jet printer provided with a novel cleaning apparatus.
[0061] Further, the invention is not limited to the embodiment as
described above. That is, various modifications can be made without
departing the scope of the invention. For example, the sound sensor
24 may be provided separately from the body 14 to transmit detected
sound data to the driving control apparatus 200 of the body 14 in a
wired manner or in a wireless manner. In such a case, the sound
sensor 24 may be provided at a position at which sound is easily
collected. Further, the setting method and the calculation method
of the threshold value R are not limited to those of the
embodiment.
[0062] In addition, the invention can be applied to an ink jet
printer with various purposes and various information management
systems and a cleaning apparatus thereof as well as a receipt
printer of a POS system and a cleaning apparatus thereof. Moreover,
the invention can be applied to various ink jet printers for an
office or a household and the cleaning apparatuses thereof.
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